In the case of semiconductor components including a drift zone and a drift control zone arranged adjacent to the drift zone, the drift control zone being insulated from the drift zone by a dielectric layer, the drift control zone provides for the formation of an accumulation channel or an inversion channel along the dielectric layer—depending on the doping type of the drift zone—when driven in the on state. Given the same on resistance as a conventional component without such a drift control zone, the accumulation or inversion channel that forms when the component is driven in the on state enables a lower doping of the drift zone, and thus a higher dielectric strength, or the channel leads to a low on resistance given the same doping of the drift zone.
For realizing vertical components, that is to say those components in which, in the on state, a current flows in a vertical direction between a front side and a rear side of the semiconductor body, it is necessary to produce dielectric layers which extend in a vertical direction of the semiconductor body over the entire depth of the drift zone. In this case, the thickness of the dielectric layer, that is to say the dimension thereof in a horizontal direction, should be as small as possible in order to achieve a best possible accumulation or inversion effect. Such dielectric layers extending in a vertical direction can be produced by using a trench etch and subsequently filling the trench with a dielectric material. However, dielectric layers having a thickness of a few hundred nm such as are desirable for such components can be produced only to a limited depth by this method. Depending on the desired dielectric strength of the component, and thus depending on the dimension of the drift zone in a vertical direction, the depth may be insufficient to produce a dielectric layer along the entire dimension of the drift zone in a vertical direction.
A further method for producing such a component provides for etching a trench that is wider than the desired thickness of the dielectric layer, applying dielectric layers to the sidewalls of the trench, and then epitaxially filling the trench with a semiconductor material. However, this method is complicated and therefore cost-intensive.